ES3009594T3 - Orthopedic break-off screws, tools for inserting such screws, and related systems - Google Patents

Abstract

A system for inserting an anchoring element into bone includes a receiving element and an anchoring element receivable therein. The receiving element is elongated along a longitudinal axis and has a proximal end and a distal end spaced apart from the proximal end along the longitudinal axis. The receiving element has an internal surface defining a transmission element. The anchoring element includes an engaging element configured to rotatably engage the transmission element such that the latter urges it in a distal direction relative to the transmission element, rotationally decoupling the engaging element from the transmission element. The distal direction extends from the proximal end to the distal end of the receiving element and is parallel to the longitudinal axis. (Automatic translation with Google Translate, no legal value)

Description

DESCRIPTION

Orthopedic cannulated screws, tools for inserting such screws and related systems

Description field

The present disclosure generally relates to bone fixation and, in particular, relates to a bone fixation element with depth control features.

Background

Bone fixation elements, including bone screws, are conventionally used to correct a variety of conditions or injuries affecting the bones of the “lesser radius” of the hands and feet. As a non-limiting example, bone screws may be used in procedures to correct hallux valgus of the foot, such as an osteotomy to correct a deformity of one or more of the hallux valgus angle (HVA) and the intermetatarsal angle (IMA), and/or an interphalangeal deformity. In particular, following the osteotomy, one or more bone screws may be used to connect the osteotomized bone segments. With bones similar in size to the smaller radii of the hands and feet, precise depth control and associated torque control of the bone screws can prevent damage to the bone segments into which the screws are inserted. However, precise depth and torque control is also beneficial for bone screws designed for insertion into other bones, including so-called long bones, such as femurs, tibias, fibulas, humerus, radii, ulnas, metacarpals, metatarsals, and phalanges, and the like. US Patent 2009/0149889 A1 describes a surgical instrument, which includes a first component and a second component movable about an axis relative to the first component. The second component is movable between a first position and a second position. Movement of the second component from the first position to the second position applies a torque to an orthopedic fixator to remove a portion of the orthopedic fixator.

Summary

The present invention is defined in the appended claims. According to one embodiment, a system for inserting an anchoring element into bone includes a receiving element and an anchoring element receivable within the receiving element. The receiving element is elongated along a longitudinal axis and has a proximal end and a distal end spaced apart from the proximal end along the longitudinal axis. The receiving element has an internal surface defining a transmission element. The anchoring element includes a coupling element configured to rotatably engage the transmission element, wherein the transmission element is configured to urge the anchoring element in a distal direction relative to the transmission element to rotationally disengage the coupling element from the transmission element. The distal direction extends from the proximal end to the distal end of the receiving element and is parallel to the longitudinal axis.

A tool used in accordance with one embodiment of the present invention for driving the anchoring element into the bone during each of a first mode of operation and a second mode of operation includes a driver (drive adapter) and a receiving element having a proximal end and a distal end spaced apart from the proximal end along a longitudinal axis. The drive adapter can be attached to the proximal end of the receiving element to rotate the receiving element about the longitudinal axis. The receiving element includes at least one torque transmitting element. In the first mode of operation, the at least one torque transmitting element is configured to engage at least a first coupling element and at least a second coupling element of a bone fixation element so as to rotate the anchoring element about the longitudinal axis. In the second mode of operation, the at least one torque transmitting element is configured to disengage from the at least one first coupling element and remain engaged with the at least one second coupling element. The tool includes a coupler coupled to each of the driver and receiver element such that, during a first portion of the first mode of operation, the driver and receiver element are movably secured relative to each other along the longitudinal axis, and during a second portion of the first mode of operation, the driver and receiver element are movable relative to each other along the longitudinal axis.

A fixation element used in accordance with one embodiment of the present invention includes an anchoring element having a proximal end and a distal end spaced apart from the proximal end along a central axis. The anchoring element has a first plurality of coupling elements sized and configured to receive a driving torque that drives the anchoring element. The fixation element includes a removable element having a proximal end and a distal end that spaced apart from the proximal end of the removable element along the central axis. The removable element joins the anchoring element at an interface, and the removable element includes a second plurality of coupling elements sized and configured to receive the driving torque. The interface is configured to fracture in response to a predetermined torque differential between the removable element and the anchoring element. The first plurality of coupling elements comprises a first plurality of projections. The second plurality of coupling elements comprises a second plurality of projections. Each of the projections of the first and second plurality of projections extends radially outward and defines a pair of opposing surfaces and a peripheral surface extending between the pair of opposing surfaces. The opposite surfaces of each pair are substantially parallel to each other and to the central axis.

Description of the drawings

The foregoing summary, as well as the following detailed description of the preferred embodiments of the application, will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the embodiments of the present application, certain embodiments are shown in the drawings. However, it should be understood that the application is not limited to the precise arrangements and instruments shown. In the drawings:

Figure 1 is a side view of a fixation element for insertion into a bone according to an embodiment of the present disclosure;

Figure 2 is a perspective view of the fixing element of Figure 1:

Figure 3 is an end sectional view of an anchoring element of the fixing element of Figure 1, taken along section line 3-3 of Figure 1:

Figure 4 is an end sectional view of a removable element of the fastener of Figure 1, taken along section line 4-4 of Figure 1:

Figure 5 is an enlarged sectional view of an attachment location between an anchoring element and a removable element of the fixation element of Figure 1, taken along a longitudinal axis of the fixation element; Figure 6 is a perspective view of a drive tool including a drive adapter and a drive sleeve, wherein the drive tool is configured to insert the fixation element of Figure 1 into a bone, according to an embodiment of the present disclosure;

Figure 7 is an exploded perspective view of the drive tool of Figure 6;

Figure 8 is a sectional view of the drive tool of Figure 6, taken along a longitudinal axis of the drive tool;

Figure 9A is an enlarged sectional view of a portion of the drive tool, as shown by the dashed rectangle B in Figure 8:

Figure 9B is an enlarged sectional view of a portion of the drive tool according to another embodiment of the present disclosure;

Figure 10 is a side view of the drive tool of Figure 6 positioned adjacent to a bone, wherein the drive adapter and fixation element are shown in an initial position relative to the drive sleeve;

Figure 11 is a side view of the drive tool of Figure 10, with the fixation element partially inserted into the bone, and the drive adapter and the fixation element remaining in the initial position relative to the drive sleeve:

Figure 12 is a side view of the drive tool of Figure 11, with the fixation element fully inserted into the bone, and the drive adapter and fixation element shown in a second position relative to the drive sleeve:

Figure 13 is a partially cut away perspective view of the distal end of the drive sleeve illustrated in Figures 7-8:

Figure 14 is an end sectional view of a distal portion of the drive sleeve, taken along section line 14-14 in Figure 11;

Figure 15 is a bottom view of the distal end of the drive sleeve shown in Figure 7;

Figure 16 is a partially cut away side view of the distal end of the drive sleeve, with the locking element shown in a fully inserted position;

Figure 17 is a sectional view of the distal end of the drive sleeve, taken along the longitudinal axis of the drive sleeve, according to another embodiment of the present disclosure; and

Figure 18 is a sectional view of the drive tool, taken along the longitudinal axis of the drive tool, according to a further embodiment of the present disclosure;

Detailed description

The present disclosure may be more readily understood by reference to the following detailed description taken in connection with the accompanying figures and examples, which form a part of this disclosure. It should be understood that this disclosure is not limited to the specific devices, methods, applications, conditions, or parameters described and/or shown herein, and that the terminology used herein is intended to describe particular embodiments by way of example only and is not intended to limit the scope of the present disclosure. Also, as used in the specification, including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context indicates otherwise.

The term “plurality,” as used herein, means more than one. When a range of values is expressed, another embodiment includes from one particular value and/or to another particular value. Similarly, when values are expressed as approximations, by use of the antecedent “approximately,” it shall be understood that the particular value forms another embodiment. All ranges are inclusive and combinable.

Figure 1 illustrates a fixation element 2 for insertion into a bone according to an embodiment of the present disclosure. The fixation element 2 may be elongated along a central axis 4 and may include a proximal end 6 and a distal end 8 spaced from the proximal end 6 along the central axis 4. The central axis 4 may define a longitudinal direction X of the fixation element 2. A radial direction R may be perpendicular to the longitudinal direction X. A distal direction may be defined as extending from the proximal end 6 of the fixation element 2 toward the distal end 8 thereof and is parallel to the central axis 4. The fixation element 2 may include a removable element 10 coupled to an anchoring element 12 that is located distally of the removable element 10 along the central axis 4. The removable element 10 may be coupled to the anchoring element 12 so as to facilitate insertion of the anchoring element 12 to a desired depth within a target bone. The fixation element 2 can be configured to receive axial and rotational driving forces to facilitate insertion into the target bone. The fixation element 2 can be configured such that, once the anchoring element 12 reaches a predetermined final depth within the target bone, the removable element 10 cleanly separates from the anchoring element 12, leaving the anchoring element 12 inserted within the target bone at the final depth.

Removable member 10 includes a proximal end 14 and a distal end 16 spaced apart from the proximal end 14 along the central axis 4. Proximal end 14 of removable member 10 may form proximal end 6 of fixation member 2. Anchoring member 12 may include a proximal end 18 and a distal end 20 spaced apart from the proximal end 18 along the central axis 4. Distal end 20 of anchoring member 12 may form distal end 8 of fixation member 2.

The removable element 10 may be attached to the anchor element 12 at an attachment location 21 located therebetween. The attachment location 21 may be characterized as an “interface” or “joint” between the removable element 10 and the anchor element 12 and may be configured to facilitate separation of the removable element 10 from the anchor element 12 in response to a predetermined operating condition. For example, the predetermined operating condition may be the predetermined final depth of the anchor element 12 or a force differential, such as a torque differential, exerted between the removable element 10 and the anchor element 12, by way of non-limiting example.

The fixation element 2 includes one or more coupling elements 22 configured to couple to the force transmission elements of a drive tool and transfer rotational driving forces from the drive tool to the fixation element 2. In this manner, the anchoring element 12 can be introduced into the target bone by the drive tool. The coupling elements 22 can be located on one or both of the removable element 10 and the anchoring element 12 of the fixation element 2.

The removable element 10 and the anchor element 12 may be monolithic with respect to one another. In such embodiments, the attachment location 21 may include a neck 23 joining the distal end 16 of the removable element 10 and the proximal end 18 of the anchor element 12. The removable element 10 may include a post 24 located proximally of the neck 23. The post 24 may be cylindrical, as illustrated; however, other post geometries are within the scope of the present disclosure. The neck 23 may have a reduced width relative to the remainder of the removable element 10, including the post 24, and may be configured to fracture in response to the predetermined operating condition, as described in more detail below. However, other brittle or detachable couplings may be used to join the anchor element 12 and the removable element 10.

As illustrated, the anchoring element 12 may be a bone screw 25 having a head 26 and a shank 28 extending distally from the head 26 along the central axis 4. The shank 28 may terminate distally in a pointed tip 30 that may also be characterized as the distal end 20 of the anchoring element 12 and the distal end 8 of the fixation element 2. The pointed tip 30 may be configured to penetrate a cortical wall of the bone. The shank 28 may include a helical thread 32 extending between the head 26 and the tip 30. The pointed tip 30 and the thread 32 may provide the bone screw 25 with self-drilling functionality. Additionally, at least one slot 34 may be formed in the shank 28 adjacent to the pointed tip 30, providing the bone screw 25 with self-tapping functionality through cortical bone material and cancellous bone material.

The engaging elements 22 of the fixation element 2 may include a plurality of projections extending radially from one or both of the removable element 10 and the anchor element 12, as also shown in Figure 2. In accordance with the present invention, the anchor element 12 includes a first plurality of projections 36 that are located adjacent to the proximal end 18 of the anchor element 12 and extend radially outwardly from the anchor element 12. In embodiments where the anchor element 12 is a bone screw 25, the projections 36 may form the head structure 26. In the illustrated embodiment of Figure 1, the first plurality of projections 36 may include four (4) projections 36 spaced at 90° intervals around the central axis 4.

As shown in Figure 3, the first plurality of projections 36 may form a crisscross pattern when viewed from the central axis 4. Each of the first plurality of projections 36 may include a pair of opposing side surfaces 38a, 38b and a peripheral surface 40 extending between the pair of opposing side surfaces 38a, 38b. One of the side surfaces 38a may be on a rotational forward side 42 of the associated projection 36 and the other of the side surfaces 38b may be on a rotational rearward side 44 of the associated projection 36. Each forward side surface 38a may form a right angle (90°) with the rearward side surface 38b of the anterior projection 36. The boundary between each adjacent rotational forward side and adjacent rotational rearward side 44, 42 may optionally be rounded to reduce stress concentrations within the anchor element 12.

The side surfaces 38a, 38b may each extend in the longitudinal direction X. In some embodiments, each of the side surfaces 38a, 38b may be substantially planar. In such embodiments, each of the side surfaces 38a, 38b may extend along a plane defined by a first direction that is parallel to the longitudinal direction X and a second direction that is perpendicular to the first direction and parallel to the radial direction R. In embodiments where the thread 32 of the anchoring element 12 is configured according to the “right-hand rule”, the rotatable forward side 42 of each projection 36 faces counterclockwise when viewed from the central axis 4 at a location distal to the distal end 8 of the fixation element 2, while the rotatable rear side 44 of each projection 36 faces clockwise when viewed from the central axis 4 at a location distal to the distal end 8 of the fixation element 2. Therefore, the rear side surfaces 38b can directly receive the rotary driving force of the driving tool.

The engaging members 22 of the attachment member 2 may also include a second plurality of projections 46 extending radially from the removable member 10. The second plurality of projections 46 may be located adjacent to the attachment location 21 and may also include four (4) projections 46 spaced at 90° intervals about the central axis 4. As shown in Figure 4, the second plurality of projections 46 may also be formed in a crisscross pattern. In the illustrated embodiment, the second plurality of projections 46 may be aligned with the first plurality of projections 36 about the central axis 4. However, it should be appreciated that in other embodiments (not shown) the first and second plurality of projections 36,46 may be offset from each other about the central axis 4.

Each of the second plurality of projections 46 may include a pair of opposing side surfaces 48a, 48b and a peripheral surface 50 extending between the pair of opposing side surfaces 48a, 48b. One of the side surfaces 48a of the second plurality of projections 46 may be on a rotatable forward side 52 of the associated projection 46 and the other of the side surfaces 48b may be on a rotatable rearward side 54 of the associated projection 46. Each forward side surface 48a may form a right angle (90°) with the rearward side surface 48b of the anterior projection 46.

Each of the side surfaces 48a, 48b of the second plurality of projections 46 may extend in the longitudinal direction X. Each of the side surfaces 48a, 48b of the second plurality of projections 46 may be substantially planar. For example, each of the side surfaces 48a, 48b may extend along a plane defined by a third direction that is parallel to the longitudinal direction X and a fourth direction that is perpendicular to the third direction and parallel to the radial direction R. In embodiments where the second plurality of projections 46 is aligned with the first plurality of projections 36 about the central axis 4, the first and third directions are parallel to each other, and the second and fourth directions are parallel to each other. Therefore, the rear side surfaces 48b can directly receive the rotary driving force of the drive tool.

Furthermore, when the first and second plurality of projections 36, 46 are aligned around the central axis 4, a projection 36 of the first plurality and an associated projection 36 of the second plurality may be characterized as a pair of projections 36, 46. Furthermore, side surfaces 38a, 38b, 48a, 48b on the same side 42, 44.

52, 54 of one of the pairs of projections 36.46 can be characterized as a pair of side surfaces 38. 48. Accordingly, a pair of side surfaces 38, 48 can be coupled by the same force transmission element of the drive tool, as explained in more detail below.

Optionally, the post 24 of the removable element 10 may have a radius R1 that is substantially equivalent to an internal radius R2 of each of the lateral surfaces 48a, 48b of the second plurality of projections 46, which allows each lateral surface 48a, 48b of the second plurality of projections 46 to be contiguous with the lateral surface 48b, 48a of the successive projection 46 about the central axis 4. Additionally, an internal radius R3 of each of the lateral surfaces 38a, 38b of the first plurality of projections 36 may be substantially equivalent to the internal radius R2 of each of the lateral surfaces 48a, 48b of the second plurality of projections 46. In this way, the force transmitting elements of the drive tool can perfectly fit into each pair of associated lateral surfaces. Therefore, the force transmitting elements of the drive tool can apply substantially the same amount of torque to each pair of associated projections 36. 46. and, therefore, the same amount of torque to the anchoring element 12 and the removable element 10 before the predetermined operating condition.

Figure 5 illustrates an enlarged sectional view of the attachment location 21 and the coupling elements 22 of the fixing element 2. As described above, the attachment location 21 may include a neck 23 having a reduced width relative to the width of the remainder of the removable element 10. In this manner, the fixing element 2 is configured to fracture cleanly at the neck 23 in response to the predetermined operating condition.

During insertion of the fixation element 2 into the bone in a first mode of operation, the force transmitting elements of the drive tool can apply a rotational force to the pairs of lateral surfaces 38, 48, resulting in a driving torque applied in the direction of the anchoring element 12 and the removable element 10. In a second mode of operation, the force transmitting elements of the drive tool can be disengaged from the posterior lateral surfaces 38b of the projections 36 of the anchoring element 12 to apply substantially all of the rotational driving force to the posterior lateral surfaces 48b of the projections 46 of the removable element 10, creating a differential in the amount of torque applied between the removable element 10 and the anchoring element 12.

The fixing element 2 may be configured so that the torque differential stress is concentrated within the neck 23, causing mechanical failure (i.e., fracture) in the neck 23 when the torque differential exceeds a predetermined value. The fixing element 2 and the driving tool may be cooperatively configured so that the torque differential exceeds the predetermined value when the predetermined operating condition occurs.

The geometries of the distal end 16 of the removable element 10, the neck 23, and the proximal end 18 of the anchor element 12 may be configured to ensure that fracture of the fixation element 2 occurs at the neck 23. In particular, the neck 23, the proximal end 18 of the anchor element 12, and the distal end 16 of the removable element 10 may be cooperatively shaped and sized to concentrate stresses within the neck 23 when a torque differential is imparted between the removable element 10 and the anchor element 12. For example, the peripheral surface 50 of each of the projections 46 of the removable element 10 may include a posterior segment 55, an intermediate segment 56 located distally of the posterior segment 55, and a frontal segment 58 located distally of the intermediate segment 56. As shown, the intermediate segment 56 may be substantially parallel to the central axis 4. The frontal segment 58 may taper inwardly toward the central axis 4 in the distal direction. As shown, the frontal segment 58 may taper distally so as to be contiguous with the neck 23.

The peripheral surface 40 of each of the projections 36 of the anchoring element 12 may include a posterior segment 60, one or more intermediate segments 62 located distally of the posterior segment 60 and a frontal segment 64 located distally of one or more intermediate segments 62. The posterior segments 60 may also be characterized as the most proximal end of the associated projections 36, of the head 26 and of the anchoring element 12. At least a portion of the posterior segment 60 may be located proximally of the neck 23 such that, after the neck 23 fractures in response to the predetermined operating condition, and after removal of the removable element 10, the fractured region of the anchoring element 12 preferably does not include any protrusions, such as a boss, fragment, or serrated edge, extending proximally beyond the posterior segment 60. It should be appreciated that any boss, fragment, serrated edge, or other protrusion extending proximally beyond the posterior segment 60 could puncture, abrade, or otherwise damage the patient's soft tissue overlying the inserted anchoring element 12. The above geometries of the removable element 10 and the anchoring element 12 adjacent the neck 23 may substantially reduce the likelihood of such occurrences.

Continuing with reference to Figure 5, the shank 28 of the anchoring element 12 may include a tapered portion 66 located distally and adjacent to the head 26. The tapered portion 66 of the shank 28 may taper inwardly toward the central axis in the distal direction. The tapered portion 66 may be sized and configured to provide the anchoring element 12 with a gradual transition between the diameter D2 of the shank 28 and an increasing diameter of the front segment 64 of the head 26 as the anchoring element 12 is inserted and the head 26 seats within the target bone. In other words, the tapered portion 66 provides for a gradual seating of the head 26 of the anchoring element 12, as well as reduce tension on the ring during insertion. The tapered portion 66 may reduce the likelihood that the target bone will split or crack at or adjacent to the location where the anchoring element 12 is inserted into the bone. The taper angle α of the conical portion 66 relative to the central axis 4 may be constant or may vary along the distal direction. By way of non-limiting example, in some embodiments, the taper angle α may be constant and may be in the range of about 0° to about 45°. In other embodiments, the taper angle α may be between about 5° and about 25°. Additionally, the front segment 64 of the peripheral surface 40 of each of the first plurality of projections 36 may have a convex arcuate profile to further provide gradual seating of the head 26 of the anchoring element 12 within the target bone. It should be appreciated that the tapered portion 66 may be omitted.

The predetermined operating condition, which triggers the separation of the removable element 10 from the anchor element 12, may be subject to a variety of factors, including, but not limited to, the identity, size, shape, and/or density of the target bone; the desired depth, axial and/or rotational insertion rate, and/or insertion angle of the anchor element 12 into the target bone; the material condition and/or optional heat treatment of any one of the fixation elements 2, the removable element 10, and/or the anchor element 12; the angle at which the front segment 58 and/or the rear segment 60 of the projections 46 are oriented relative to the central axis 4, etc. The dimensions and material composition of the fixation element 2, including the neck 23, for example, may be tailored to account for the foregoing factors. It should be appreciated that the predetermined operating condition may also be triggered unilaterally by a user, such as a physician, by manually fracturing the neck 23.

The removable element 10 may have a length L<i>in the range of about 20 mm to about 50 mm or more, measured from the proximal end 14 to the distal end 16 of the removable element 10. In some embodiments, the removable element 10 may have a length t<i>in the range of about 20 mm to about 35 mm. In further embodiments, the removable element 10 may have a length L<i>in the range of about 35 mm to about 50 mm. In further embodiments, the removable element 10 may have a length L<i>greater than 50 mm or even greater than 100 mm. In other embodiments, the removable element 10 may have a length L<i>in the range of about 1 mm to about 20 mm, including a range between about 1 mm and about 5 mm.

The post 24 of the removable element 10 may have a diameter D<1> in the range of about 0.5 mm to about 4.0 mm. In some embodiments, the post 24 may have a diameter D<1> in the range of about 0.5 mm to about 0.8 mm. In other embodiments, the post 24 may have a diameter D<1> in the range of about 0.8 mm to about 1.5 mm. In further embodiments, the post 24 may have a diameter D<1> in the range of about 1.5 mm to about 2.5 mm. In further embodiments, the post 24 may have a diameter D<1> in the range of about 2.5 mm to about 4.0 mm. In still further embodiments, the post 24 may have a diameter D<1> greater than 4.0 mm. It should be appreciated that in embodiments where the diameter D<1> of the post 24 is in the range of about 0.8 mm to about 2.5 mm, the post 24 may provide the advantage of being able to be coupled to and driven by a cable drive, such as a Kirschner wire (“K” wire) drive.

The shank 28 of the anchoring element 12 may have a diameter D<2> in the range of about 0.5 mm to about 4.0 mm or more. For example, the shank 28 may have a diameter D<2> in the range of about 0.5 mm to about 1.5 mm. In other embodiments, the shank 28 may have a diameter D<2> in the range of about 1.5 mm to about 2.0 mm. In other embodiments, the shank 28 may have a diameter D<2> in the range of about 2.0 mm to about 2.7 mm. In further embodiments, the shank 28 may have a diameter D<2> in the range of about 2.7 mm to about 3.5 mm. In further embodiments, the shank 28 may have a diameter D<2> in the range of about 3.5 mm to about 4.0 mm. In still further embodiments, the stem 28 may have a diameter D<2> greater than 4.0 mm. Additionally, the threads 32 may be sized and pitched to facilitate smooth insertion, as well as self-drilling and/or self-tapping functionality.

The fixation element 2 may be formed of a material including one or more of a titanium-aluminum-vanadium alloy (such as Ti-6A1-4V, also referred to as “TAV”), a titanium-aluminum-niobium alloy (such as Ti-6Al-7Nb, commonly referred to as “TAN”), steel, such as stainless steel, or any alloy comprising the same. In further embodiments, the fixation element 2 may be formed of a thermoplastic polymer, such as a polyetheretherketone (PEEK) material, although it should be appreciated that in such embodiments, pre-drilling may be necessary prior to inserting the anchoring element 12 into the bone. It should be appreciated that the fixation elements 2 may be comprised of any suitable biocompatible material known in the art.

In an illustrative, non-limiting embodiment, the post 24 may have a diameter D<1>of about 1.4 mm and a length L<1>of at least about 20 mm; the shank 28 of the anchoring element 12 may have a diameter D<2>of about 2.0 mm; and the neck 23 may have a diameter D<3>of about 0.8 mm. In this example, the neck 23 may fracture when the torque differential between the removable element 10 and the anchoring element 12 is about 0.93 N*m. Furthermore, through numerous tests, the inventors surprisingly and unexpectedly discovered that, at the above dimensions of this exemplary embodiment, the fixation element 2 comprised of TAN produced a flatter, less jagged fracture profile at the neck 23 than other materials, thereby reducing the likelihood of protrusions, fragments, or other protrusions projecting proximally beyond the posterior surface 60 of the head 26 of the anchoring element 12. The fixation element 2 sized and configured according to the above example may be advantageously suitable for insertion within a “minor radius” of a foot, such as is typical for certain hallux valgus correction procedures, including osteotomies. It should be appreciated that the above exemplary embodiment may also be advantageously suitable for other surgical procedures. ;It should be appreciated that the fixation element 2 described herein is not limited to any particular size, as the fixation element 2 and its constituent components can be scaled to virtually any size to accommodate any use, including use in long bones, by way of non-limiting example. Accordingly, at any size of the fixation element 2, the diameter D1 of the post 24, the diameter D2 of the shank 28, the diameter D3 of the neck 23, and/or the size of any or all of the coupling elements 22 can be adapted to achieve separation from the removable element 10 when the predetermined operating condition occurs. ;It should also be appreciated that, while the fixation element 2 depicted in Figures 1-4 illustrates the coupling elements 22 of each of the removable elements 10 and the anchor element 12 forming a crisscross pattern, any geometry of the coupling elements is within the scope of the present disclosure. For example, in other embodiments (not shown), the coupling elements 22 may form a hexagonal pattern, a star-shaped pattern, or any other pattern that allows it to receive a driving torque from the driving tool and transmit the torque to the fastener element 2. In other embodiments, instead of projections 36, 46 extending from the anchor element 12 and the removable element 10, respectively, the head 26 of the anchor element 12 and an associated head of the removable element 10 may each have a generally circular cross-sectional profile in a plane orthogonal to the central axis 4, wherein the coupling elements 22 include recesses extending toward the respective heads in the radial direction R. In such embodiments, the respective circular heads of the anchor element 12 and the removable element 10 may each include two or more recesses evenly spaced from each other about the central axis 4. In other embodiments, other geometries of the coupling elements 22 are contemplated. 6 illustrates an insertion system 100 for inserting the fixation element 2. The system 100 includes a drive tool 102 that is configured to receive the fixation element 2 and drive the fixation element 2 toward the target bone until the fixation element 2 reaches a predetermined depth within the bone. The drive tool 102 may define a longitudinal axis Z and may include a drive adapter 104 and a drive sleeve 106 that is carried by the drive adapter 104. The drive adapter 104 may include a proximal end 108 and a distal end 110 spaced apart from the proximal end along the longitudinal axis Z. The drive sleeve 106 may include a proximal end 112 that is receivable over the distal end 110 of the drive adapter 104. As shown, the distal end 110 of the drive adapter 104 is receivable within the drive sleeve 106. The drive sleeve 106 may include a distal end 114 spaced apart from the proximal end 112 of the sleeve along the longitudinal axis Z. Relative to the drive tool 2, and also relative to the fixation element 2 received therein, the distal direction may be defined as extending from the proximal end 108 of the drive adapter toward the distal end 114 of the drive sleeve 106 and is parallel to the longitudinal axis Z. The drive adapter 104 is movable relative to the drive sleeve 106 along the longitudinal axis Z between an initial position and a fully inserted position, the latter position occurring when the anchoring element 12 is inserted into the target bone to a predetermined final depth. The drive adapter 104 is configured to apply the axial driving force directly to the fixation element 2 and the drive sleeve 106 is configured to apply the rotational driving force directly to the fixation element 2. ;The fixation element 2 can be received at least partially within the drive adapter 104 and coupled thereto. For example, the distal end 110 of the drive adapter 104 can include a mandrel 116 (see Figure 7) configured to receive the proximal end 14 of the post 24 of the fixation element 2. The drive sleeve 106 can define a central hole 118 and can have a length sufficient to receive and surround the majority of the fixation element 2 when the fixation element 2 is loaded within the mandrel 116. Accordingly, the drive sleeve 106 can be referred to as a “receiving element.” In the initial position, the proximal end 14 of the removable element 10 of the fixation element 2 can be received within the drive adapter 104 and coupled thereto, while only the stem 28 of the anchoring element 12 extends beyond a distal end 114 of the drive sleeve 106. When the drive sleeve 106 is in the fully inserted position relative to the drive adapter 104, all of the anchoring element 12, except for a portion of the head 26, may be located distally of the distal end 114 of the drive sleeve 106, as described in more detail below. Referring now to Figure 7, the drive adapter 104 may include a body 120, also referred to as an “adapter body,” which may be generally cylindrical, although other geometries are within the scope of the present disclosure. The adapter body 120 may be characterized by having a proximal portion 122 adjacent the proximal end 108 of the adapter, a distal portion 126 adjacent the distal end 110 of the adapter, and an intermediate portion 124 located longitudinally between the proximal portion 122 and the distal portion 126. It should be appreciated that a proximal end 128 of the adapter body 120 may form the proximal end 108 of the drive adapter 104. The adapter body 120 may have a distal end 130 spaced apart from the proximal end 128 of the adapter body 120 along the longitudinal axis Z. The distal end 130 of the adapter body 120 may mate with a distal end of the mandrel 116. An end cap 131 may be coupled to the mandrel 116 such that a distal end 132 of the end cap 131 may form the distal end 110 of the drive adapter 104. Thus, the proximal end 108 of the drive adapter 104 may be synonymous with the proximal end 128 of the adapter body 120; the distal end 130 of the adapter body 120 may be synonymous with the distal end of the mandrel 116; and the distal end of the drive adapter 104 may be synonymous with the distal end of the end cap 131. The proximal portion 122 of the adapter body 120 may define an outer surface 144 and one or more gripping features formed on the outer surface 144. The one or more gripping features may provide gripping for a user's hand or a power tool for operating the drive tool 102 to insert the anchoring element 12 into the target bone. By way of non-limiting example, the gripping features may include a recessed platform 136 on the adapter body 120 adjacent the proximal end 108 thereof. The platform 136 may extend in a direction parallel to the longitudinal axis Z and may be contiguous with the outer surface 144 of the adapter body 120. As shown, the platform 136 may be substantially planar, although it should be appreciated that other geometries are within the scope of the present disclosure. The gripping features may also include an annular recess 138 formed in the outer surface 144 of the adapter body 120 at or adjacent the proximal end 108 thereof. The adapter body 120 may include and/or carry one or more engaging elements for engaging with various components of the drive sleeve 106 and the attachment element 2. The drive sleeve 106 may have a sleeve body 140 having a tubular, generally cylindrical shape and defining the central sleeve bore 118, which extends from the proximal end 112 to the distal end 114 of the sleeve body 140. Accordingly, the sheath body 140 may be characterized as a “tubular body.” The sheath body 140 may include a sheath wall 142 extending radially between an outer surface 144 of the sheath body 140 and an inner surface 146 of the sheath body 140. The sheath body 140 may be characterized by having a proximal portion 148 adjacent the proximal end 112 of the drive sheath 106, a distal portion 152 adjacent the distal end 114 of the sheath, and an intermediate portion 150 located longitudinally between the proximal portion 148 and the distal portion 152. The outer surface 144 of the sheath body 140 at the distal portion 152 thereof may have a reduced diameter relative to that of the outer surface 144 at the proximal portion 148. The intermediate portion 150 of the sheath body 140 may be characterized by tapering in the distal direction. In other words, the outer surface 144 of the sheath body 140 may include a taper 153 that mates with the intermediate portion 150 of the sheath body 140. The drive sleeve 106 may also include one or more attachment elements that are complementary and configured to couple directly or indirectly with at least one of the one or more coupling elements of the adapter body 120. For example, the proximal portion 148 of the drive sleeve 106 may include a first attachment element 154 configured to couple to a first coupling element 156 of the distal portion 126 of the adapter body 120. In particular, the first attachment element 154 of the sleeve body 140 may include the inner surface 146 of the sleeve body 140 within the proximal portion 148 thereof, as shown in Figure 8, which illustrates a sectional view of the drive tool 2 along the longitudinal axis Z. With continuing reference to Figures 7 and 8, the associated first coupling element 156 of the adapter body 120 may include a cylindrical outer surface 158 of the adapter body. 120 within the distal portion 126 thereof. The cylindrical outer surface 158 of the distal portion 126 of the adapter body 120 and the inner surface 146 of the proximal portion 148 of the sleeve body 140 may be cooperatively sized and configured such that the inner surface 146 of the sleeve body 140 at the proximal portion 148 thereof slidably engages and translates over the cylindrical outer surface 158 of the distal portion 126 of the adapter body 120 during use of the drive tool 102. For example, the cylindrical outer surface 158 of the distal portion 126 of the adapter body 120 may have a diameter substantially equivalent to or slightly smaller than the diameter of the inner surface 146 of the proximal portion 148 of the sleeve body 140, which facilitates translational engagement between the distal portion 126 of the adapter body 120 and the proximal portion 148 of the sleeve body 140. The distal portion 126 of the adapter body 120 may also carry a second engaging member 160, which may be configured to retain the drive sleeve 106 to the drive adapter 104 during operation. The second engaging member 160 may include a pin 162 received in a first transverse bore 164 that extends through the distal portion 126 of the adapter body 120 and intersects the longitudinal axis Z of the drive tool 102. The pin 162 may have a length greater than the diameter of the cylindrical outer surface 158 of the distal portion 126 of the adapter body 120 such that each opposite end of the pin 162 projects from the cylindrical outer surface 158. The one or more engaging members of the drive sleeve 106 may include a pair of opposing slots 166, each formed through the sleeve wall 142 and extending longitudinally along at least a portion of the sleeve body 140. When the proximal end 112 of the sleeve body 140 is received over the cylindrical outer surface 158 of the distal portion 126 of the adapter body 120, the opposite ends of the pin 162 may extend radially through the pair of opposed slots 166 of the sleeve body 140 so as to retain the proximal portion 148 of the drive sleeve 106 in the distal portion 126 of the drive adapter 104. Each of the opposite ends of the pin 162 may have a diameter substantially equal to or slightly less than the circumferential width of each of the two opposed slots 166, so that the pin 162 can translate along the slots 166 during use of the drive tool 102. In this manner, the orientation of the opposing slots 166 along the sleeve body 140 may control at least an extent of the translational and rotational movement of the drive sleeve 106 relative to the drive adapter 104, as set forth in more detail below. Accordingly, the slots 166 may be referred to as “guide slots” and the pin 162 may be referred to as a “follower pin” or “follower”. The drive tool 102 includes a biasing member 170 that biases the drive sleeve 106 into the initial position relative to the drive adapter 104. The biasing element 170 may be disposed between a first shoulder 172 located on the distal portion 126 of the adapter body 120 and an opposing second shoulder 174 formed on the inner surface 146 of the sheath body 140, as shown in Figure 8. The first shoulder 172 may be positioned distally of the first cross-hole 164. The second shoulder 174 may be located proximally of the taper 153 of the outer surface 144 of the sheath body 140 and thus may be characterized as being located on the proximal portion 148 of the sheath body 140, as shown in the illustrated embodiment. Alternatively, the second shoulder may be located on the intermediate portion 150 or on the distal portion 152 in other embodiments. The first shoulder 172 may face substantially in the distal direction and the second shoulder may face substantially in the proximal direction. The biasing element 170 may include a compression spring 176, although other types of biasing elements 170 are within the scope of the present disclosure. The one or more coupling elements of the adapter body 120 may include a third coupling element 178, which may be configured to receive the proximal end 14 of the post 24 of the fixation element 2. The third coupling element 178 may include the mandrel 116, which may define a central hole 180 formed in the distal portion 126 of the adapter body 120. The central hole 180 may extend from the distal end 130 of the adapter body 120 in the proximal direction. The central hole 180 may optionally intersect a second transverse hole 182 extending through the distal portion 126 of the adapter body 120. The second transverse hole 182 may be positioned longitudinally between the first transverse hole 164 and the distal end 130 of the adapter body 120. The second transverse hole 182 may also be located distally of the first shoulder 172 in the mating body 120. In the illustrated embodiment, a central axis of the second cross hole 182 may optionally be offset by an angle of approximately 45° relative to a central axis 184 of the first cross hole 164 about the longitudinal axis Z. However, in other embodiments (not shown), the first and second cross holes 164, 182 may be parallel to each other, or may have any other orientation relative to each other. As shown in Figures 7 and 8, the second cross-hole 182 may mate with the terminal end of the central hole 180 of the mandrel 116. Thus, a rear inner surface of the second cross-hole 182 may transmit the axial driving force to the anchoring element 12 through the post 24. The central hole 180 may have an inner diameter substantially equivalent to or slightly larger than the diameter D<1> of the post 24, so that the proximal end 14 of the post 24 may be received (i.e., “loaded”) within the central hole 180. The third coupling element 178 of the drive adapter 104 may include a retaining element 186 configured to hold the post 24 of the fixing element 2 within the central hole 180 of the mandrel 116. The retaining element 186 may impart to the post 24 a retaining force (i.e., in the proximal direction) that is at least greater than the gravitational force of the fixing element 2, thereby preventing the post 24 from sliding out of the central hole 180 due to gravity. The retention force may also be sufficient to prevent the post 24 from sliding out of the central hole 180 due to additional inertial forces associated with regular use of the drive tool 102. Accordingly, the retaining element 186 may allow a physician to insert the fixation element 2 at an inclined angle without the post 24 slipping off the mandrel 116. The retaining element 186 may be disposed within the end cap 131 mounted on the mandrel 116. Figure 9A is an enlarged view of the portion of the drive tool 102 indicated by the dashed rectangle B of Figure 8. The end cap 131 may define a central bore 188 sized to receive the post 24. It should be appreciated that any manner of coupling the end cap 131 to the mandrel 116 is within the scope of the embodiments described herein. The retaining element 186 may be received within an annular recess 189 formed in the central bore 189 of the mandrel 116 at the distal end 130 thereof. The retaining element 186 may abut a proximal end 133 of the end cap 131 so as to retain the retaining element 186 in the annular recess 189. The retaining element 186 may be a spring 192 having a resilient body with an inner diameter slightly smaller than the diameter D<1> of the post 24 to provide the retaining force to the post 24. The spring 192 may be a polymeric ring element that is compressed within the annular recess 189 by the proximal end 133 of the end cap 131 when the end cap 131 is fully seated relative to the mandrel 116 to provide the spring 192 with an inner diameter slightly smaller than the diameter D<1> of the post 24. However, it should be appreciated that other types of retaining elements may be used to prevent the post 24 from slipping out of the cylindrical bore 180 during normal use of the tool. 102 drive are within the scope of the present disclosure. By way of non-limiting example, retaining member 186 may include a circular coil spring, a rubber ring gasket sized to provide a friction fit with post 24, a spring-loaded ball and groove retaining arrangement on post 24 and center bore 188, respectively, and a tapered distal end of mandrel 116 sized to grip onto post 24. Figure 9B illustrates an alternative end cap 131 arrangement, wherein end cap 131 defines a sleeve received over mandrel 116. In this arrangement, spring 192 may be disposed within center bore 188 of end cap 131 between distal end 130 of mandrel 116 and an opposing abutment surface 191 formed within center bore 188 of end cap 131. The abutment surface 191 may be oriented perpendicular to the longitudinal axis Z of the drive tool 102. The spring 192 may be compressed between the distal end 130 of the mandrel 116 and the abutment surface 190 when the end cap 131 is fully seated relative to the mandrel 116 to provide the spring 192 with an inner diameter slightly smaller than the diameter D<1> of the post 24. ;Referring again to Figure 8, the drive sleeve 106 includes force transmitting elements 200 located on the distal portion 152 of the sleeve body 140. The force transmitting elements 200 may be formed on the inner surface 146 of the sleeve body 140 and configured to engage the engaging elements 22 of the fastener 2 to provide the rotational driving force to the fastener 2, as described in more detail below. ;;Referring now to Figures 10-12, various steps of the drive tool 102 are illustrated during the first mode of operation (i.e., during insertion of the anchor element 12 to the predetermined final depth). In particular, Figure 10 illustrates the drive tool 102 holding the anchor element 12 adjacent an external surface 300 of a target bone 302 in the orientation in which the anchor element 12 is to be inserted. The drive adapter 104 and the drive sleeve 106 in Figure 10 are shown in the initial position. Each of the opposing slots 166 may include a first portion 166a and a third portion 166c separated by a second intermediate portion 166b. The first and third portions 166a, 166c of each slot 166 may each extend in a direction parallel to the longitudinal axis Z and may be circumferentially displaced relative to each other about the longitudinal axis Z. The second portion 166b of each slot 166 may extend in a circumferential direction. In the first slot portion 166a, the sleeve wall 142 may define a first end 251, a second end 252 opposite and distally spaced apart from the first end 251, and lateral sides 261, 262 extending between the first and second ends 251. In the second slot portion 166b, the sleeve wall 142 may define a third end 253, a fourth end 254 opposite and circumferentially spaced from the third end 253, and lateral sides 263, 264 extending between the third and fourth ends 253, 254. In the third slot portion 166c, the sleeve wall 142 may define a fifth end 255, a sixth end 256 opposite and distally spaced from the fifth end 255, and lateral sides 265, 266 extending between the fifth and sixth ends 255. 256. One of the lateral sides 261, 262 of the sleeve wall 142 at the first portion 166a of the slots 166 may be a rotatably forward side 261, and the other may be a rotatably rearward side 262. In embodiments where The drive tool 102 is configured to insert the anchor element 12 according to the “right-hand rule”, the rotatable forward side 261 of the wall 142 in the first slot portion 166a is located on the left side of the slot 166, as illustrated in Figures 10-12, and the rotationally rearward side 262 of the wall 142 in the first slot portion 166a is located on the right side of the slot 166. The pin 162 may transfer most, or even substantially all, of the rotational driving force from the adapter body 120 to the sleeve body 140 by driving against the rotatable forward side 261 of the sleeve wall 142 in the first slot portion 166a of each of the slots 166. It should be appreciated that, in a fastener 2 designed for insertion according to the right-hand rule, the threads 32 of the stem 28 of the anchoring element 12 are angled such that clockwise rotation of the anchoring element 12, as viewed from the central axis 4 or longitudinal axis Z at a location proximate the proximal end 18 of the anchoring element 12, causes the threads 32 to engage the bone (or whatever material the anchoring element 12 is being inserted into) so as to drive the anchoring element 12 toward the bone. In the initial position, the pin 162 may abut the first end 251 of the first slot portion 166a. As the drive adapter 104 is pushed distally and rotated about the longitudinal axis Z, axial and rotational driving forces are applied to the fixation element 2, causing the anchor element 12 to engage and penetrate the target bone 302. The biasing element 170 may provide an axially opposing biasing force greater than the axial force necessary to penetrate the target bone 302, such that, as the anchor element 12 is inserted deeper into the target bone 302, the drive adapter 104 remains in the initial position relative to the drive sleeve 106 as the distal end 114 of the drive sleeve 104 approaches the outer surface 300 of the target bone 302. Therefore, during a first portion of the first mode of operation (i.e., until the distal end 114 of the drive sleeve 106 contacts the outer surface 300 of the target bone 302), The biasing element 170 holds the drive adapter 104 and the drive sleeve 106 in a fixed and translatable position relative to each other along the longitudinal axis Z. It should be appreciated that the biasing element 170 may be characterized as a “coupler” or a “coupling element”. ;;As can be seen in Figure 11, the drive adapter 104 and the fixation element 2 remain in the initial position until the distal end 114 of the drive sleeve 106 contacts the external surface 300 of the target bone 302. Referring now to Figure 12, as the drive tool 102 continues to drive the anchoring element 12 toward the target bone 302, the abutment of the drive sleeve 106 against the external surface 300 of the target bone 302 may prevent further distal translation of the drive sleeve 106 relative to the target bone 302. However, the axial biasing force of the biasing element 170 is selected to be overcome by the axial driving force required for the anchoring element 12 to further penetrate the target bone 302 after the distal end 114 of the drive sleeve 106 contacts the target bone 302. Thus, after the distal end 114 of the drive sleeve 106 abuts the outer surface 300 of the target bone 302, and the drive tool 102 is pressed with an axial force sufficient to drive the anchoring element 12 further toward the target bone (i.e., during a second portion of the first mode of operation), the drive adapter 104 and the fixation element 2 are longitudinally displaced relative to the drive sleeve 106 in the distal direction. At the same time, pin 162 moves distally along opposed slots 166 from first end 151 toward second end 252 of first portion 166a of each of slots 166. Thus, pin 162 may provide a user with a direct visual indication of the longitudinal position of the drive adapter (and thus an indirect visual indication of the longitudinal position of fastener 2) relative to drive sleeve 106. Cylindrical outer surface 158 on distal portion 126 of adapter body 120 may also include indicia 340, such as sequential lines, to provide a user with another visual indication of the various longitudinal positions of fastener 2 relative to drive sleeve 106. Sleeve body 140 may also define a second plurality of opposed slots 193 located at least partially in distal portion 152 of the sleeve body. Each of the second pair of opposing slots 193 may extend radially through the sheath wall 142 and may provide the user with a direct visual indication of the longitudinal position of the fixation element 2 within the drive sheath 106, even after the distal end 114 of the drive sheath 106 contacts the bone 302. The second pair of opposing slots 193 may also provide an opening for effluent, such as blood, marrow and/or other bone cuttings, to escape from the distal portion 152 of the sheath body 140 and avoid clogging or impeding use of the drive tool 102. ;;Figure 12 illustrates the drive adapter 104 and the fixation element 2 in the fully inserted position relative to the drive sleeve 106, in this position the anchoring element 12 is fully inserted to the predetermined final depth within the target bone 302 and the drive tool 102 enters the second mode of operation, wherein each projection 36 of the anchoring element 12 clears the rotatable front surface 208 of each tab 202, as set forth in more detail below. Additionally, in the fully inserted position, the pin 162 may be spaced apart from the first end 251 and located near the second end 252 of the first portion 166a of each slot 166, but may also remain in contact with the rotatable rearward side 262 of the sleeve wall 142 within the first portion 166a of each of the slots 166. Additionally, as the drive adapter 104 and the locking member 2 move distally relative to the drive sleeve 106 from the initial position to the fully inserted position, the engaging members 30 of the locking member 2 move distally along the force transmitting members 200 of the drive tool 102. ;The third portions 166c of the pair of opposing slots 166 may allow the user to fully retract the drive sleeve 106 relative to the drive adapter 104 for cleaning or other purposes before, during, or after use of the drive tool during the first and second modes of operation. For example, the user may manually retract the drive sleeve 106 relative to the adapter 104 to clean or inspect the attachment element 2 during use. The intermediate portion 124 of the adapter body may include a protrusion 194 defining a shoulder 196 configured to abut the proximal end 112 of the sleeve 106 so as to limit proximal translation of the drive sleeve 106 relative to the adapter body 120. The second portions 166b of the pair of opposing slots 166 allow a user to rotate the drive sleeve 106 relative to the adapter body 104 to pass the pin 162 from the first portion 166a to the second portion 166b of the slots 166. In some embodiments (not shown), the lower lateral side 263 of the second portion 166b of each of the slots 166 may be tilted in the distal direction so that the pin 162 automatically passes from the second portions 166b of the slots 166 to the first portions 166a in response to the biasing force of biasing element 170 if the user inadvertently leaves adapter 104 and sleeve 104 in relative positions such that pin 162 is positioned in second portion 166b or third portion 166c of slots 166. Referring now to Figure 13, force transmitting elements 200 include a plurality of tabs 202 extending radially inwardly from inner surface 146 of sleeve body 140 toward longitudinal axis Z of drive tool 102. Each of tabs 202 may also extend substantially longitudinally from a proximal end of tab 204 to a distal end of tab 206. Distal ends 206 of tabs 202 may mate with distal end 114 of drive sleeve 106. Each tab 202 includes a rotatable forward surface 208 and a rotatable rearward surface 210. Each of the rotatable forward and rearward surfaces 208, 210 may be substantially planar, although other geometries are within the scope of the present disclosure. Each of the tabs 202 may have a longitudinal length greater than a maximum longitudinal distance between the rearward segment 55 of the projections 46 of the removable element 10 and the front segment 64 of the projections 36 of the anchoring element 12. Thus, when the sleeve 106 is in the initial position relative to the drive adapter 104, each tab 202 may span at least the entire length of each pair of projections 36, 46. In this manner, the tabs 202 may provide radial support to the fixing element 2 and prevent the neck 23 from deforming under the axial driving force. ;;As shown in Figure 14, the number of tabs 202 of the drive sleeve 106 may match the number of associated pairs of projections 36, 46 of the attachment element 2. For example, in embodiments where the attachment element 2 includes four (4) associated pairs of projections 36, 46, the sleeve body 140 may include four tabs 202 spaced at 90° intervals about the longitudinal axis Z of the drive tool 2. Additionally, the rotatable front and rear surfaces 208, 210 of each tab 202 may extend at right angles (90°) relative to one another. In such embodiments, the rotatable forward surface 208 of each tab 202 may be parallel to the associated pair of side surfaces 38b, 48b on the rotatably forward sides 44, 54 of the associated pairs of projection 36, 46 of the fastener 2 when the forward surface 208 of each tab 202 abuts the associated pair of rearward side surfaces 38b, 48b. Additionally, the rotatable rear surface 210 of each tab 202 may be parallel to the associated pair of side surfaces 38a, 48a on the rotatably forward sides 42, 52 of the associated pairs of projection 36, 46 when the rear surface 210 of each tab 202 abuts the associated pair of front side surfaces 38a, 48a. In further embodiments, the tabs 202 of the sleeve body 140 and the pairs of projections 36, 46 of the fixation element 2 may each be sized and cooperatively configured such that the tabs 202 fit snugly between abutting side surfaces 38, 48 of the mating pairs of projection 36, 46 of the fixation element 2, providing stability to the drive tool 2 and the fixation element 2 during insertion of the anchoring element 12 into the target bone. As the drive adapter 104 and the fixation element 2 move relative to the drive sleeve 106 from the initial position to the fully inserted position, the pairs of side surfaces 38, 48 of the mating elements 22 of the fixation element 2 move distally along the tabs 202 of the drive sleeve 106. ;;Referring now to Figures 13 and 15, the distal end 206 of each tab 202 may define a ramped surface 212 inclined toward the direction of rotation. A rotatable leading edge 214 of each ramped surface 212 may be adjacent the rotatable leading surface 208 of the associated flange 202. A rotatable trailing edge 216 of each ramped surface 212 may be adjacent the distal end 114 of the drive sleeve 106. The ramped surface 212 of each tab 202 may be sized and oriented to provide a longitudinally located space between each ramped surface 212 and the distal end 114 of the drive sleeve 106. The rotatable leading edge 214 of each ramped surface 212 may be spaced apart from the distal end 114 of the drive sleeve 106 by a separation distance, measured in the longitudinal direction. The standoff distance may be equal to or slightly greater than the seating distance of the anchoring element 12, as measured between the posterior segment 60 of the projection 36 and the outer surface 300 of the bone 302 when the anchoring element 12 is inserted to the predetermined final depth. The portion of the anchoring element 12 located above the outer surface 300 of the bone 302 when the fixation element 12 is inserted to the predetermined final depth may be referred to as the “outer portion.” Each of the ramped surfaces 212 of the tabs 202 may be oriented at an angle 0 between about 0° and about 90° relative to a direction perpendicular to the longitudinal axis Z. In other embodiments, the ramped surfaces 212 may each be oriented at an angle 0 between about 35° and about 65° relative to the direction perpendicular to the longitudinal axis Z.

Figure 16 illustrates an enlarged side view of the distal end 114 of the drive sleeve 106, where the drive sleeve 106 is partially cut away so as to illustrate the fixation element 2 in the fully inserted position relative to the drive sleeve 106 (i.e., the anchoring element 12 is inserted into the target bone 302 to the predetermined final depth). As can be seen, a portion of the projection 36 of the anchoring element 12 is positioned longitudinally below the rotatable forward edge 214 of the ramped surface 212 at the distal end 206 of an adjacent tab 202. In this manner, once the anchoring element 12 reaches the predetermined final depth (i.e., the fully inserted position), the drive tool 102 enters the second mode of operation wherein each projection 36 of the anchoring element 12 clears the rotatable forward surface 208 of each tab 202. However, the rotatable forward surfaces 208 of the tabs 202 may remain engaged with the rotatable rear surfaces of the projections 46 of the removable element 10, imparting a majority, or even substantially all, of the rotatory driving force to the projections 46 of the removable element 10. In this manner, a torque differential is imparted between the removable element 10 and the anchoring element 12. The diameter D3 of the neck 23 can be sized so that the torque differential sufficient to fracture the neck 23 is less than the torque differential required to further rotate the anchoring element 12 after the projections of the anchoring element 12 have cleared the rotatable forward surfaces 208 of the tabs 202. Thus, the insertion system 100 can be precisely designed and configured to cause the fixation element 2 to fracture at the attachment location 21 once the anchoring element 12 reaches the predetermined final depth in the bone 302.

Additionally, once the neck 23 fractures, the drive adapter 104 and drive sleeve 106, with the removable member 10 of the fixation member 2 remaining coupled thereto, may continue to rotate relative to the fully inserted anchor member 12 about the longitudinal axis Z. The ramped surfaces 212 of the tabs 202 may engage the outside of the projections 36 of the anchor member 12 so as to allow the distal ends 206 of the tabs 202 to slide up and over the outside portions without providing sufficient torque to the outside portions to further rotate the anchor member 12. In this manner, continued rotation of drive sleeve 106 after anchoring element 12 has reached the predetermined final depth cannot cause excessive rotation of anchoring element 12 within target bone 302. Thus, it can be understood that in some embodiments, following fracture of neck 23, tabs 202 do not drive anchoring element 12 further into bone 302 as posterior segments 60 of projections 36 of anchoring element 12 are distally spaced from rotatable forward surfaces 208 of tabs 202. Accordingly, detrimental effects on the patient resulting from excessive rotation or over-seating of anchoring element 12 can be avoided. Furthermore, the tabs 202, their ramped surfaces 212, and their distal ends 206 may be characterized as depth control features, in that the separation distance at the distal ends 206 of the tabs and the size and orientation of the ramped surfaces 212 may effectively determine the insertion depth at which the anchoring element 12 stops rotating and is further inserted into the target bone 302. Additionally, the tabs 202, their ramped surfaces 212, and their distal ends 206 may be characterized as torque control features, in that the maximum torque applied to the anchoring element 12 may be a determining factor in the predetermined final depth to which the anchoring element 12 is inserted.

Referring again to Figure 15, the rotatable rear surface 210 of each tab 202 at the distal end 206 thereof may define a portion 220, also referred to as a “reverse engaging portion,” which may be flush with the distal end 114 of the drive sleeve 106. The reverse engaging portions 220 of the tabs 202 will now be described. As stated above, the rotatable rear surface 210 of each tab 202 may be parallel to the side surface 38a on the rotatable forward side 42 of the associated projection 36 of the anchor element 12 when the rear surface 210 of the tab 202 abuts the forward side surfaces 38a. Thus, once the anchoring element 12 is inserted to the predetermined final depth, the ramped surfaces 212 allow the distal ends 206 of the tab to slide up and over the outer portions of the anchoring element projections 36 and subsequently back down to engage the outer surface 300 of the bone 302, once the tabs 202 are rotated into the space between successive projections 36.

If the physician desires to withdraw (i.e., unscrew) the anchoring element 12, he or she may position the distal end 114 of the drive sleeve 106 over the exterior of the anchoring element such that the tabs 202 are positioned between successive outer portions of the projections of the anchoring element 12 and the distal end 114 of the drive sleeve 106 is in contact with the bone surface 254. The physician may drive the sleeve 106 in the reverse direction, wherein the reverse engaging portions 220 of the tabs 202 may engage exterior portions of the rotatable forward side surfaces 38a of the associated projections 36 with sufficient torque to cause the anchoring element 12 to recoil from the target bone. In this manner, the insertion system 100 described herein can provide an operator, such as a physician, with finely tuned depth control in both the forward (i.e., distal) and rearward (i.e., proximal) directions.

Referring now to Figure 17, a distal end 114 of the drive sleeve 106 is shown in accordance with a further embodiment, wherein like reference numerals refer to like components of the embodiments discussed above. In particular, in the embodiment of Figure 17, the tabs 202' do not include ramped surfaces 212 adjacent the distal end 114 of the drive sleeve 106. Instead, in this further embodiment, the entire distal end 206' of each tab 202' may be located proximally of the distal end 114 of the drive sleeve 106 by the standoff distance. In such an embodiment, the tabs 202' may apply the torque differential between the anchoring element 12 and the removable element 12 sufficient to fracture the neck 23 therebetween, but will not provide recoil functionality once the anchoring element 12 has cleared the distal ends 206' of the tabs 202'. However, as in the embodiments illustrated above, excessive rotation of the anchoring element 12 within the target bone may be prevented.

Figure 18 illustrates a drive system 100 according to a further embodiment, wherein like reference numerals refer to like components of the embodiments discussed above. In the embodiment of Figure 18, the anchor element 12" is not coupleable to a removable portion 10. Instead, the drive tool 102" may carry a biasing element 400 configured to abut the proximal end 18" of the anchor element 12" so as to provide the axial driving force to the anchor element 12" during insertion. The rotational driving force may be applied to the projections 36 of the anchor element 12" by the tabs 202 in the manner discussed above.

In yet another embodiment, a kit may include a plurality of fixation elements 2, each of the plurality of fixation elements 2 comprising a different configuration, size, or material. The kit may further contain a plurality of drive sleeves 106 associated with the various sizes of the fixation elements 2. The kit may be especially useful in trauma settings, due to its ease of use and simplicity.

It should be appreciated that the fixation elements 2 and associated drive tools 102 described herein may also be configured and used to fix bone plates of various sizes and configurations to the bone.

Although various embodiments have been described in detail, it is to be understood that various changes, substitutions and alterations may be made herein without departing from the scope of the disclosure as defined in the appended claims.

Claims (1)

i. A system for inserting an anchoring element into the bone at a predetermined depth, the system comprising: a drive tool (102") comprising a drive adapter (104) and a receiving element (106), the receiving element (106) is elongated along a longitudinal axis (Z), the receiving element (106) has a proximal end (112) and a distal end (114) separated from the proximal end (112) in a distal direction along the longitudinal axis (Z), the receiving element (106) has an inner surface (146) defining a transmission element (200); an anchoring element (12") receivable within the receiving element (106), the anchoring element (12") having a coupling element (22) configured to rotatably engage the transmission element (200); and wherein the drive adapter (104) can be attached to the proximal end (112) of the receiving element (106), wherein the drive adapter (104) is configured to apply an axial driving force to the anchoring element (12") by means of a thrust element (400) that is carried by the drive tool (102") and the receiving element (106) is configured to apply a rotary driving force directly to the fixing element (2) to drive the anchoring element (12) towards the bone; wherein the coupling element (22) comprises: a first plurality of projections (36) extending radially outwardly from the anchoring element (12"), the transmission element (200) comprises a plurality of tabs (202) extending radially inwardly from the inner surface (146) of the receiving element (106), and the plurality of tabs (202) define rotatable forward surfaces (208) that are configured to engage the first plurality of projections (36) to apply a rotational driving force to the anchoring element (12"), characterized by: the system includes a biasing element (170) that couples to the drive adapter (104) and the receiving element (106) and provides a biasing force that is axially opposite to the axial driving force, and the drive tool (102") is configured to drive the anchoring element (12") toward the bone (300) in the distal direction such that: the biasing force is sufficient to hold the drive adapter (104) and the receiving element (106) in a fixed position and translate relative to each other along the longitudinal axis (Z) until the distal end (114) of the receiving element (106) contacts an outer surface (302) of the bone (300), after the distal end (114) of the receiving element (106) contacts the outer surface (302) of the bone (300), the axial driving force overcomes the biasing force such that the driver (104) drives the anchoring element (12) toward the bone (302) and the drive adapter (104) and the anchoring element (12") move longitudinally relative to the receiving element (106) in the distal direction until the anchoring element (12") is fully inserted to the predetermined depth at which each of the first plurality of projections (36) clears a corresponding rotatable front surface (208) of each tab (202). 2. The system of claim 1, wherein the drive tool (102) is configured to abut a proximal end (6) of the anchoring element (12) to apply the axial driving force to the anchoring element (12) in the distal direction while the coupling element (22) is rotationally coupled with the transmission element (200). 3. The system of claim 1, wherein the anchoring element (12) comprises a bone screw (25) having a head (26) and a stem (28) extending from the head (24) in the distal direction, and the head (26) defines the coupling element (22). 4. The system of claim 1, wherein each of the plurality of projections (36) is separated from a circumferentially successive projection (36) of the plurality of projections (36) by a recess. 5. The system of claim 4, wherein each of the plurality of tabs (202) is releasable in the recess between the circumferentially successive projections (36) of the plurality of projections (36). The system of claim 1, wherein each of the plurality of projections (36) comprises a rotatable forward surface (38a) and a rotatable rear surface (38b) that is parallel to the rotatably forward surface (38a). The system of claim 6, wherein each rotatable forward surface (38a) of the plurality of projections (36) is perpendicular to a rotatable rearward surface (38b) of a circumferentially successive projection (36) of the plurality of projections (36). The system of claim 7, wherein each of the plurality of tabs (202) also defines a rotatable rear surface (210), and the plurality of tabs (202) and the plurality of projections (36) are cooperatively sized and configured such that each of the rotatable front surfaces (208) of the plurality of tabs (202) is parallel with an associated rotatable rear surface (38b) of the plurality of projections (36) when each of the rotatable front surfaces (208) of the plurality of tabs (202) abuts the associated rotatable rear surface (38b) of the plurality of projections (36). A system for inserting an anchoring element into bone at a predetermined depth, the system comprising: a drive tool (102) comprising a drive adapter (104) and a receiving element (106), the receiving element (106) is elongated along a longitudinal axis (Z), the receiving element (106) has a proximal end (112) and a distal end (114) separated from the proximal end (112) in a distal direction along the longitudinal axis (Z), the receiving element (106) has an inner surface (146) defining a transmission element (200); a fixation element (2) that includes a removable element (10) and an anchor element (12) that can be received within the receiving element (106), the anchor element (12) has a coupling element (22) configured to be rotatably coupled to the transmission element (200), the removable element (10) is coupled to the anchor element (12) by a frangible or detachable coupling configured to fracture, wherein the anchor element (12) is located distally of the removable element (10) and can be received within the receiving element (106); and wherein the drive adapter (104) can be attached to the proximal end (112) of the receiving element (106), wherein the drive adapter (104) is configured to apply an axial driving force to the fixation element (2) and the receiving element (106) is configured to apply a rotational driving force directly to the fixation element (2) to drive the anchoring element (12) towards the bone, wherein the coupling element (22) comprises: a first plurality of projections (36) extending radially outwardly from the anchoring element (12) and a second plurality of projections (46) extending radially outwardly from the removable element (10), the transmission element (200) comprises a plurality of tabs (202) extending radially inwardly from the inner surface (146) of the receiving member (106), and the plurality of tabs (202) define rotatable front surfaces (208) that are configured to couple the first and second plurality of projections (36, 46) to apply a rotational driving force to the anchoring element (12), characterized in that: the system includes a biasing element (170) that couples to the drive adapter (104) and the receiving element (106) and provides a biasing force that is axially opposite to the axial driving force, and the drive tool (102) is configured to drive the anchoring element (12) toward the bone (300) in the distal direction such that: the biasing force is sufficient to maintain the drive adapter (104) and the receiving element (106) in a fixed position and translate relative to each other along the longitudinal axis (Z) until the distal end (114) of the receiving element (106) contacts an outer surface (302) of the bone (300), after the distal end (114) of the receiving element (106) comes into contact with the external surface (302) of the bone (300), the axial driving force overcomes the biasing force so that the driver (104) drives the anchoring element (12) towards the bone (302) and the drive adapter (104) and the fixation element (2) move longitudinally relative to the receiving element (106) in the distal direction until the anchoring element (12) is fully inserted to the predetermined depth at which each of the first plurality of projections (36) clears a corresponding rotatable front surface (208) of each tab (202). 10. The system of claim 9, wherein the transmission element (200) is located adjacent the distal end (114) of the receiving element (106), each of the tabs (202) defines a proximal end (204) and a distal end (206), the distal end (206) of each tab (202) is spaced from the proximal end (204) of the tab (202) in the distal direction, and the distal end (206) of the tab (202) is adjacent the distal end (114) of the receiving element (106). 11. The system of claim 10, wherein the tab (202) further comprises: a rotatable rear surface (210) when the receiving element (106) rotates around the longitudinal axis (Z); and a ramped surface (212) having a rotatable forward edge (214) adjacent the rotatable forward surface (208), and a rotatable rearward edge (216) adjacent the distal end of the tab (202). 12. The system of claim 11, wherein: the distal end (114) of the receiving element (106) is spaced from the rotatable leading edge (214) of the ramp surface (212) in the distal direction by a first distance; and The tabs (202) are configured to urge the anchoring element (12) toward the bone in response to rotation of the receiving element (106) about the longitudinal axis (Z) until the distal end (114) of the receiving element (106) is separated from a proximal end of each of the first plurality of coupling elements (36) in the distal direction by a second distance that is less than the first distance. 13. The system of claim 9, wherein the receiving element (106) comprises a guide element (166), and the drive tool (102) comprises a follower (162) configured to move within the guide element (166) to control a rotational position of the receiving element (106) relative to the drive tool (102). 14. The system of claim 9, wherein the drive device (102) comprises: a hole (180) having a central axis coincident with the longitudinal axis (Z), the hole (180) sized and configured to receive a proximal end (6) of the anchoring element (12); and a retention element (186) received within the hole (180), the retention element (186) configured to engage the anchoring element (12) to prevent the anchoring element (12) from detaching from the hole (180) in response to a gravitational force from the anchoring element (12). 15. The system of claim 9, wherein the drive tool (102) is configured to abut a proximal end (6) of the anchoring element (12) to apply the axial driving force to the anchoring element (12) in the distal direction while the coupling element (22) is rotationally coupled with the transmission element (200). 16. The system of claim 9, wherein the anchoring element (12) comprises a bone screw (25) having a head (26) and a stem (28) extending from the head (24) in the distal direction, and the head (26) defines the coupling element (22). 17. The system of claim 9, wherein each of the plurality of projections (36) is separated from a circumferentially successive projection (36) of the plurality of projections (36) by a recess. 18. The system of claim 17, wherein each of the plurality of tabs (202) is releasable in the recess between the circumferentially successive projections (36) of the plurality of projections (36). 19. The system of claim 9, wherein each of the plurality of projections (36) comprises a rotatable front surface (38a) and a rotatable rear surface (38b) that is parallel to the rotatable front surface (38a). 20. The system of claim 19, wherein each rotatable forward surface (38a) of the plurality of projections (36) is perpendicular to a rotatable rearward surface (38b) of a circumferentially successive projection (36) of the plurality of projections (36). 21. The system of claim 7, wherein each of the plurality of tabs (202) also defines a rotatable rear surface (210), and the plurality of tabs (202) and the plurality of projections (36) are cooperatively sized and configured such that each of the rotatable front surfaces (208) of the plurality of tabs (202) is parallel with an associated rotatable rear surface (38b) of the plurality of projections (36) when each of the rotatable front surfaces (208) of the plurality of tabs (202) abuts the associated rotatable rear surface (38b) of the plurality of projections (36).